Update to drupal 8.0.0-rc1. For more information, see https://www.drupal.org/node/2582663

vendor/symfony/debug/Resources/ext/tests/003.phpt

@@ -0,0 +1,85 @@
+--TEST--
+Test ErrorHandler in case of fatal error
+--SKIPIF--
+<?php if (!extension_loaded("symfony_debug")) print "skip"; ?>
+--FILE--
+<?php
+
+namespace Psr\Log;
+
+class LogLevel
+{
+    const EMERGENCY = 'emergency';
+    const ALERT = 'alert';
+    const CRITICAL = 'critical';
+    const ERROR = 'error';
+    const WARNING = 'warning';
+    const NOTICE = 'notice';
+    const INFO = 'info';
+    const DEBUG = 'debug';
+}
+
+namespace Symfony\Component\Debug;
+
+$dir = __DIR__.'/../../../';
+require $dir.'ErrorHandler.php';
+require $dir.'Exception/FatalErrorException.php';
+require $dir.'Exception/UndefinedFunctionException.php';
+require $dir.'FatalErrorHandler/FatalErrorHandlerInterface.php';
+require $dir.'FatalErrorHandler/ClassNotFoundFatalErrorHandler.php';
+require $dir.'FatalErrorHandler/UndefinedFunctionFatalErrorHandler.php';
+require $dir.'FatalErrorHandler/UndefinedMethodFatalErrorHandler.php';
+
+function bar()
+{
+    foo();
+}
+
+function foo()
+{
+    notexist();
+}
+
+$handler = ErrorHandler::register();
+$handler->setExceptionHandler('print_r');
+
+if (function_exists('xdebug_disable')) {
+    xdebug_disable();
+}
+
+bar();
+?>
+--EXPECTF--
+Fatal error: Call to undefined function Symfony\Component\Debug\notexist() in %s on line %d
+Symfony\Component\Debug\Exception\UndefinedFunctionException Object
+(
+    [message:protected] => Attempted to call function "notexist" from namespace "Symfony\Component\Debug".
+    [string:Exception:private] => 
+    [code:protected] => 0
+    [file:protected] => %s
+    [line:protected] => %d
+    [trace:Exception:private] => Array
+        (
+            [0] => Array
+                (
+%A                    [function] => Symfony\Component\Debug\foo
+%A                    [args] => Array
+                        (
+                        )
+
+                )
+
+            [1] => Array
+                (
+%A                    [function] => Symfony\Component\Debug\bar
+%A                    [args] => Array
+                        (
+                        )
+
+                )
+%A
+        )
+
+    [previous:Exception:private] => 
+    [severity:protected] => 1
+)